an analytical solution of the equation describing diffusion of intrinsic point defects in semiconductor crystals has been obtained for a one-dimensional finite-length domain with the robin-type boundary conditions. the distributions of point defects for different migration lengths of defects have been calculated. the exact analytical solution was used to verify the approximate numerical solutio...

the feasibility of extractive reaction of methacrylic acid from aqueous solution using a quaternary amine, tri–octyl methyl ammonium chloride (tomac) as an extractant, was studied. the diluents chosen in the present work belong to different chemical classes, n–butyl acetate, carbon tetrachloride, isoamyl alcohol, methyl isobutyl ketone, and toluene. the effect of initial acid concentration in t...

the purpose of this study was to elucidate some factors affecting the growth of salmonella typhimurium. these factors included carum copticum essential oil (0%, 0.015%, 0.03% and 0.06%), temperature (25 ˚c and 35 ˚c), ph (5, 6 and 7) and inoculum size (103 and 105  cfu ml-1). brain heart infusion broth was used as the growth medium. there were 48 treatment combinations and the experiment was ca...

background: in large cities, the share of vehicles in air pollutants emissions is nearly 70% that is mainly due to use of fossil fuels. environmental simulation has many advantages such as accuracy and speed of modeling. present study was conducted to create a model of air pollution [carbon monoxide (co) and nitrogen oxides (nox)] from vehicles in fifty following years, in mashhad. methods: acc...

little is known about the interaction of tissue conditioners and modeling plastics. this study evaluates the influence of a variety of commercial tissue conditioners on alteration of viscoelastic properties of modeling plastics.in this in vitro study, the dynamic viscoelastic properties of four commercially available tissue conditioners (tc), visco-gel (vg), gc soft-liner (sl), fitt (ft), and c...

in this study, the possibility of microwave finish drying for two types of dried grapes (natural and sultana) was investigated. the samples were washed in water bath at given temperature ranges (25 and 45 c) for 30 to 60 minutes. after dewatering the samples, they were dried using microwave (at two powers: 270 and 450 w) and hot air convective dryer (at 50 c). water gain (%), effective moistu...

viscosity (µ) and density (ρ) are important physical roperties for analysis of membrane processes performance and for designing a new membrane process. in addition, the energy requirement for fluid pumping is depend on these two physical properties magnitiude. in this study, firstly, the effects of different process factors such as transmembrane pressure (51, 101, 152, 203 and 253 kpa), tempera...

in this research, first, kinematic and dynamic equations of a 4-dof 3-link robotic finger are derived using denavit-hartenberg convention and lagrange’s formulation. to model the muscles, several springs and dampers are placed between the finger links. then, two advanced controllers, namely adaptive-robust and adaptive-neural, which can control the robotic finger in presence of parametric uncer...

background: nowadays the eutrophication of water bodies is enhanced due to discharge of effluents and runoffs. therefore, there is a demand for the management of natural and artificial lakes to prevent or postpone this problem. lakes eutrophication is a complex process. therefore computerized models are very important tools to describe this process. although there are several models for this, b...

conclusions the results indicated that the model, compared with other models, was user-friendly and the desired results were obtained by a minimal data. materials and methods the current paper developed a process model. first, a sketch of nitrate and ammonia storage, their specifications and parameters were set out and created on a page, and then, mathematical relations of each process were set...